Recent advances in LNG liquefaction processes have made LNG an attractive energy source, and various commercial users have begun to explore LNG uses in applications other than natural gas production. However, currently known LNG regasification processes often require considerable fuel gas consumption for heating. Alternatively, and where available, the heat content of seawater using open rack seawater heaters may be used to regasify the LNG. Unfortunately, LNG seawater heaters have a negative environmental impact on the ocean life from the cold seawater discharge, and seawater systems tend to be costly. Additional problems are present where the heating value of the LNG varies among shipments, or where a particular LNG composition is not suitable for a specific market. Therefore, LNG must often be processed to conform to the heating value, Wobbe Index, and composition required by local environmental regulations and combustion equipment specifications, thereby further adding to the cost of production.
Recently, various configurations have been proposed that accommodate LNG with varying composition as described in our copending International patent application with the serial number PCT/US03/25372, which is incorporated by reference herein. Furthermore, a portion of the power consumed in liquefaction is recoverable at the receiving terminal when LNG is used as a heat sink for power generation, and/or as fuel for a power plant. Such and other configurations are described in our copending International patent applications with the serial numbers PCT/US03/26805, and PCT/US05/24973, all of which are incorporated by reference herein.
While all or almost all of such improved configurations and methods provide at least some advantages over previously known configurations, various disadvantages nevertheless remain. Among other things, most of the known plants will either produce an ethane and/or C3+ fraction, or take advantage of the refrigeration content of LNG. However, currently known configurations to condition import LNG typically require stripping and recompression, which are inefficient and costly. In addition, these processes are inadequate for processing rich LNG while producing ethane and LPG products for sales and co-generating power. Therefore, there is still a need to provide improved plant configurations and methods in which the rich LNG is processed while producing ethane, LPG and power.